Cell signal transduction pathways play important roles in cell growth, proliferation and differentiation. The Ras/Raf/MEK/ERK pathway is a primary signal transduction pathway, which transmits signals from multiple cell surface receptors to transcription factors that regulate gene expression in the cell nucleus. It has been found that abnormal activation of the Ras/Raf/MEK/ERK pathway is often observed in malignant transformed cells, and accordingly it is believed that inhibition of the pathway is beneficial for treating hyperproliferative diseases. MEK is a key member in this pathway as it is downstream of Ras and Raf. In addition, since currently known substrates of MEK phosphorylation are merely MAP kinases, ERK1 and ERK2, MEK is an attractive therapeutic target. Several studies have found that inhibition of MEK has potential therapeutic benefits.
Chinese Patent Application No. CN102020651A discloses a compound of formula I, of which the chemical name is 6-(2-chloro-4-iodophenylamino)-N-(2-hydroxyethoxy)-5-methyl-4-oxo-4,5-dihydrofuro[3,2-c]pyridine-7-carboxamide. The compound is a MEK kinase inhibitor, and can be used for the treatment and/or prophylaxis of proliferative diseases, such as inflammatory diseases or tumors, in particular, melanoma.

Since the compound of formula I has a low solubility and a low dissolution rate, it difficultly dissolves out after being formulated into a preparation, resulting in its poor druggability. In order to solve the above-mentioned problem, an active compound is usually transformed into a salt form. For example, Selumetinib, a compound structurally similar to the compound of formula I, has a structure as shown in formula II, and its preparation is disclosed in Chinese patent application CN102046156A.

However, such compounds have weaker alkalinity. After being transformed into a salt, they are particularly susceptible to dissociation into their free base forms during preparation processing (especially industrial production) and/or storage, thereby reducing their bioavailability and affecting their therapeutic effect. Therefore, such compounds need a complex preparation process and excipients to prepare a formulation, but the final result is not satisfactory.
Accordingly, there is a continuing need for a pharmaceutical composition capable of improving the dissolution and bioavailability of the compound of formula I.